chore: add FAL_KEY env var to docker-compose

Required for Fal.ai FLUX img2img in zine regeneration

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker-compose.yml

@@ -12,6 +12,7 @@ services:
       - PORT=3000
       - GEMINI_API_KEY=${GEMINI_API_KEY}
       - RUNPOD_API_KEY=${RUNPOD_API_KEY}
+      - FAL_KEY=${FAL_KEY}
     volumes:
       - zine-data:/app/data
     networks: